Today i was hooking up one of my 6s batteries to the charger only half concentrating on what i was doing and I must have accidentally bridged between the + and - bullet connectors with the male bullet of the charging cable.
There was a big flash and this is what the 5.5mm bullets looked like a millisecond later:
The burned male (red) connector on the left is the charger cable, the two connectors on the right are the +/- off the battery, all are beefy 5.5mm bullets. the spark blew the end off one bullet and burned a hole straight through the side of the other!
Luckily that was all the damage apart from a couple of tiny burns on my finger caused by flying molten metal (sounds worse than it was). Normally I keep a cap over the male (negative) battery terminal until I've connected the positive side up, but today I must have been daydreaming.. There's a lesson to be learned - Always concentrate when working with LiPos!!
This wasn't the only lesson though. I went about replacing the battery bullet connectors. These were original factory supplied connectors on the Turnigy LiPos.
Here's what the soldering socket of the male connector looked like:
Notable is the TOTAL lack of any solder in the socket:eek: All that was connecting the wire to the bullet was a thin fillet of solder between the side of the wire and the edge of the bullet, and that only ran around half the circumference. I shudder when I think I was pulling 140A through that connector.
So lesson number two - Re-solder every connector on your LiPos! (especially cheap ones)
Oops! Thanks for swallowing your pride and sharing that with us, and glad there wasn't any major injury or damage. A good lesson.
i think they call that ark welding lol
I hate that when that happens :( I have done that too :D It sure is a wake up Call :Q
Thats very scary seeing the lack of solder in that bullet!
I did almost exactly the same thing one time. I was charging at the field and one of the exposed male bullets touched the frame on my truck while connecting the charger.
I not only ruined the connector I shorted, but I also blew one of the aluminum tabs on one of the cells in the pack. It blew just like a fuse.
It took me a while to figure out why the pack read zero voltage after I soldered on a new connector! I knew it couldn't possibly have discharged down to zero that quickly.
Not paying attention can get expensive!
140 Amps through that??? You're right, that was very fortunate to not have blown out in flight.
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